1. Field of the Invention
The present invention relates to a chloroprene rubber composition and an adhesive composition using the same. More specifically, it relates to a chloroprene rubber composition superior in discoloration resistance under heat or light and an adhesive composition prepared using the chloroprene rubber composition.
2. Description of the Related Art
Chloroprene rubbers are materials superior in heat resistance, weather resistance, ozone resistance, chemical resistance, flame resistance (self-extinguishing) and others and have been used in various applications. A typical application among them is adhesive application.
Chloroprene rubber-containing adhesives generally known are those prepared by dissolving a mixture of polychloroprene, adhesive resins, metal oxides, and others in an organic solvent such as toluene or acetone. Such adhesives are superior in initial adhesive strength and others and have been used in various applications including shoes, woodworks, furniture, and vehicles (see, for example, Patent Documents 1 and 2).
Although chloroprene rubbers with balanced physical properties have been used in various fields, as described above, they have a disadvantage that they easily discolor to yellow or brown when exposed to heat or light, and in some cases, the disadvantage restricted their use, depending on the application.
There were proposed methods for improving the discoloration resistance of chloroprene rubbers. For example, Patent Document 3 describes a method of producing a chloroprene rubber, comprising using an alkali-metal salt of disproportionated rosin acid and a water-soluble polymer having sulfonic acid groups and/or sulfate ester groups introduced by addition polymerization and/or addition polymerization and subsequent polymer reaction as dispersants during radical emulsion polymerization in water and adding a radical scavenger and an ultraviolet absorbent thereto at the end of the polymerization.
Patent Document 4 describes a method of using a polymerization inhibitor composition comprising a 4-(C1-C3-alkoxy)phenol and a hindered bis(phenol)methane represented by a particular Chemical Formula, wherein the molar ratio of the alkoxyphenol to the hindered bis(phenol)methane is in the range of 0.5/1 to 2.5/1 during emulsion polymerization of chloroprenes.